Method of making glass fiber web



April 1962 E. w. CURRIER 3,031,360

METHOD OF MAKING GLASS FIBER WEB Filed May 27, 1960 44 .ll lll l ll ilfliflliflfi NVENTOR.

llll ll ll ll lllllili. 44 EVERETT w. CURRIER :lll ll l ll lhllli. By miillllllllillllllll v C ATLORNEY United States Patent ()ii Bflilfitt Patented Apr. 24, 1962.

ICC

This invention relates to the method of making a glass fiber filamentous mat or web containing a series of spaced, generally longitudinally extending reinforcing elements.

Elongated, expanded thickness glass fiber webs convolutely wound into rolls to provide a preformed package have. come into substantial use as air filter medium supply packages adapted for use in automatic renewable medium air filters of the so-called roll type. The principle of operation of such, filters includes unwinding and passing the medium from a supply roll positioned at one end of an air stream aperture, through the aperture where the medium filters particulate matter from the stream, and into a dischargezone at the opposite, end of the air stream aperture where the used medium is reroll'ed into a compact disposable package.

In such use of, the elon'--.

gated web, some ditficulty has been experienced .asa result of the tensile force applied to the medium 'for re,

tional view, partly in section, of apparatus for processing rolling and to eflect its advancecausing the medium to elongate and neck in the air stream witha resultant loss of the air seals along the edges of medium; Such culty has been particularly experienced with those media which include structural characteristics similar to a lazy tongs structure. Consequently, reinforcing material, in the form of scrim, wires and the like has been applied to such media to obviate the difiiculty, with such material normally being applied to such webs in a step separate, from the fabrication of the web itself.

A principal object of the present invention is the pro visionof a method of farbicating or making a glass fiber web containing reinforcing elements within the web, with the elements being applied during an intermediate fabricating step in which the web. is undergoing a change in itsstruotural character.

Specific objects include the provision of a method for fabricating such a Web wherein guide elements for feeding: reinforcing elements into the interior of the web are applied to. a cylindrical condensed mat during its fabrication, and. the reinforcing elements are fed into the web while the condensed mat is being transformed in structural character to'an elongate, expanded thickness web by stretching.

In carrying out the inventive method, certain conventional glass fiber web fabricating steps are practiced, including, feeding a plurality of glass fiber filaments from a feeder moving in a reciprocating path axially along a filament receiving drum rotating a plurality of times during each feeder traverse so as to build up a cylindrical condensed mat on the drum, slitting the cylindrical condensed mat axially and removing it from the drum to form a planar condensed mat, stretching the planar condensed mat in a direction transverse to the general lay of the filaments to form an elongate expanded thickness web, and further treating the web to-iform a finished web of the character desired;

Briefly, in accordance with the invention, the cylindrical condensed mat formed on the rotating drum is formed of an inner succession of layers of filaments, and an outer succession of layers of filaments. Between the steps of spinning the inner and outer successions of layers of filaments, a plurality of hollow tubes are secured to the drum in circumferentially spaced, generally axially extending relation so as to be elfective'ly sandwiched between the inner and outer successions of layers with the tubes extending generally transversely to the lay of the filaments. During stretching of the planar condensed mat comprised of the successions of layers containing the sandwiched series of tubes, a corresponding series of reinforscing filaments are fed through the tubes into an intermediate depth stratum of the expanded thickness web which is being formed by progressively stretching the mat. Preferably the reinforcing filaments are coated with an adhesive serving to cause the glass fiber filaments contacting the reinforcing filaments to adhere thereto.-

Other objects and features of the invention will be ap preciated from the following explanation to be taken in connection with the accompanying drawing illustrating apparatus adapted to be used in carrying out the principles of the invention, and wherein:

FIGURE 1 is a partly broken somewhat diagrammatic front elevational view showing the cylindrical condensed mat being formed with axially extending hollow tubes in place;

FIGURE 2 is a somewhat diagrammatic side elevational view of the apparatus in FIGURE 1;

FIGURE3 is a fragmentary isometric view of an end portion of the drum illustrating one manner in which the hollow tubes may conveniently be affixed to the drum;

FIGURE 4 is a somewhat diagrammatic side elevaa planar condensed mat formed with the apparatus of FIGURES 1 and 2;

FIGURE 5 is a partly broken, somewhat diagrammatic top view of a part of the apparatusshown in FIGURE 4; and

' FIGURE 6 is a schematic top view of a planar condensed mat containing tubes disposed in one alternative arrangement.

Referring to FIGURES 1 and 2 of the drawing, the cylindrical drum 2 supported by opposite end shafts 4 is rotated a multiplicity of times during each traverse of the glass furnace 6 which is driven in a reciprocating path axially along, and back and forth between the opposite end areas of, the drum. Preferably, the furnace driving means (not shown) is of the type disclosed in Jackson US. Patent 2,798,531, issued July 9, 1-957, so as to provide afurnace traversing speed which is varied in a cyclically repetitive pattern between maximum and minimum values one or more times during each traverse and with the filament patterns of every other filament layer being offset.

Glass fibers 8 which issue from the furnace'fi are deposited upon the circumferential surface of the drum (which is first Wrapped with a paper covering to facilitate ultimate removal of the condensed mat from; the drum) in successive layers which each contain a'multiplicity of helical turns of filaments extending continuously from one end area to the other end area of the drum. It will be appreciated: that since the furnace traverses the drum in first one direct-ion, and then the opposite. direction, the filaments forming successive layers ofthe condensed mat will lie in crossing relationship.

After building up a first or inner succession oflayers of condensed mat, indicated in FIGURE 1 by the numeral 10, the drum and furnace are stopped to permit securing a plurality of axially extending hollow tubes 12 to the drum. The tubes may be fixed to the drum by any of various methods such as taping the ends of the tubes to the drum on the end areas of the drum extending beyond the edges of the condensed mat, by applying the tubes in the form of a preformed web, or in accordance with a preferred method of this invention by secur'mg them in a jig adapted to receive the tube ends. The preferred jig arrangement illustrated (FIGURES 1-3) includes a pair of arc-like members 14 shaped to conform on their inner edges to the curvature of the drum and fixed on the extreme opposite circumferential end areas of the drum beyond the edges of the condensed mat and parallel thereto. Each arc-like member 14 is provided with an equal number of circumferentially spaced notchlike openings 16, each of which is aligned axially with the corresponding opening in the opposite member 14. The opposite end openings 16 of each member 14 may span a circumferential portion of the drum which is somewhat less than the contemplated final width of the web to be stretched from the condensed mat.

In the preferred method of fixing the tubes 13 to the drum, the tube material is a flexible plastic such as Teflon spaghetti of about A outside diameter, and of a sufficient length to extend back and forth across the drum enough times to make-up the number of tubes desired plus the necessary length to extend along the end area of drum between openings l6. A knot 18 is tied in one end of such a continuous length of material and is disposed to be secured or hooked adjacent one end opening 16 in one of the members 14. The material is then laid axially across the drum and underlying inner succession of layers 10, threaded through or positioned in an opposing end opening in the opposite end member 14, is then bent to follow the outer surface of the same member to the adjacent opening through which it is passed to extend axially back across the drum to the other member 14, and is thus laid back and forth across the drum to form a network of axially extending tubes spaced circumferentially around a portion of the drum, with a second knot 20 being tied in the material to secure the final end in its opening.

After applying the network of tubes over the particular area of the mat as illustrated, the drum 2 is again rotated while the furnace 6 is reciprocated back and forth to form an overlying second or outer succession of layers 22 of condensed mat with the tubes sandwiched between the inner and outer layers in that portion of the cylindrical mat across which they extend. Preferably the last or outer layer of the inner succession of layers contains filaments extending in a helix in one direction while the first or inner layer of the outer succession of layers 22 is formed of filaments extending in an oppositely directed helix. The initial layers of the outer succession of layers tend to secure the central portion of the tubes to the drum to resist the centrifugal force tending to throw the tubes off the drum.

Since the weight of the members 14 extending along only a portion of the drum circumference would provide an unbalanced condition of the rotating drum, suitable counter weights 24 are secured on the end wall surfaces of the drum at diametrically opposite locations to the center of mass of the members 14. The axial line upon which the final cylindrical condensed mat is to be slit for removal of the drum is also diametrically opposite to an axial line extending centrally through the tube network, this slit line being indicated in FIGURE 2 by the dotted line 26.

After the cylindrical condensed mat formed of the first and second succession of layers with the tubes 12 sandwiched between is formed, the tube material is cut where it extends between adjacent openings 16 on each end of the drum, and the cylindrical condensed mat is slit axially along the line 26 and unwrapped, along with the underlying paper which is stripped from the mat prior to stretching, from the drum to provide a planar condensed mat 30 illustrated in FIGURES 4 and 5 as being supported by a table 32. This planar condensed mat is then stretched or elongated in a direction transverse to the general lay of the filaments to form an expanded thickness web 34- of substantially reduced width relative to the original length of the planar condensed mat. This stretching or expansion step also causes the fibers to assume an orientation in which nearly all of the fibers have a diagonal disposition of one degree or another with many of the fibers having varying degrees of corrugation or waviness. The expanded thickness web is advanced into a heat treating oven 36 which includes an upper and lower endless foraminous conveyor 38 and 40 which serves to support and compress the web to the desired thickness as it is being passed through the oven to set or cure the binder in the web. As the web exits from the oven it is rolled up to form a preformed roll 32 of material suitable for use as a filtering medium.

In accordance with the invention, as the planar condensed mat 30 is being progressively stretched by advancing successive incremental portions of the mat width to form the elongate web 34-, a plurality of reinforcing elements 44 are fed through the stationary tubes 12 and into the interior of the expanded web 34 for passage therewith during further treatment. While the reinforcing elements may be any properly selected material, one suitable material is 30 gauge bookbinder steel wire which may be unwound from a bank of spools 46 mounted behind the trailing edge of the condensed mat. A corresponding bank of nozzles 48 located between the spools and tubes, and in alignment therewith, receive the wires 44 and coat them with an adhesive supplied from a tank 50 mounted above the nozzles 48 and connected thereto by suitable piping to supply the adhesive in proper quan-' tities by gravity feed. While various adhesives may be used for coating the wire depending upon the curing practice, one suitable adhesive is a polyester resin mixed with powdered silica; one such resin being commercially available by the designation Polyite 8006 sold by the Reich hold Chemical Company. As will be readily appreciated, the adhesive coating on the wires 44 causes the wires and filaments contacting them to adhere, and as they pass through the heat treating oven 36 the adhesive is set or cured along with the binder material on the fibers.

It is here believed noteworthy that before the condensed planar mat is begun to be stretched by advancing its leading edge toward the oven 36, one wire 44 is threaded by means of a thin, stifl rod or the like through each of the tubes 12 and suitably secured to a transverse rod of bar which is advanced into the oven 36 with the leading edge of the elongate expanded thickness web 34. By means of this arrangement it is insured the wires will advance simultaneously into and move along with the web without slippage.

As noted previously, it is preferable that the layers of filaments immediately adjacent opposite sides of the tube contain filaments extending in oppositely directed helical angles as they are spun on the drum. The purpose of this arrangement is to the inward lateral dis placement of the outer wires as they issue from the lead ing edges of the tubes and into the expanded thickness web which narrows as it is initially stretched. With the filaments of the layers adjacent each side of the wire ex tending in crossing relationship, the forces exerted by the filaments upon the wire during the stretching step w' tend to oppose each other so that the wires will feed longitudinally through the expanded web at approximate ly the same lateral spacing as the tubes within the condensed mat.

However, the lateral spacing between wires in the expanded web may vary in accordance with various factors such as: the amount and nature of binder applied to the filaments as they are being spun; the amount and nature of binder applied to the wires 44 as they are passed through the tubes; and, the width to which the condensed mat is stretched. Thus under certain conditions it may be desirable to space the tubes 12 on the drum farther apart adjacent one end of the drum than at the other end so that a pattern of tubes in the planar condensed mat would appear as schematically illustrated in FIGURE 6 wherein the tubes are not only spaced farther apart than the tubes illustrated in FIGURE 5, but are also arranged to form a converging pattern in the planar condensed mat. With such a tube arrangement, the wires fed through the tubes advance within the web in a pattern conforming more closely to the outline of the expanded web as it is being stretched. i

It is noted that While the condensed mat has been "described as being formed of filaments deposited on the drum individually, in accordance with known practices part or all of the filaments may be gathered into groups for deposition on the drum in that form.

The invention claimed is: r

1. The method of making a filamentous web of the character described comprising: reciprocating -a filament feeder axially back and forth along the drum; rotating said drum a multiplicity of times during each traverse of said feeder; feeding a plurality of filaments from said feeder to said drum during each-traverse to build upia first condensed filamentous mat containing a plurality of layers of filaments with the filaments of adjacent layers lying in crossing relationship; stopping said drum and said feeder; securing a series of spaced tubes in generally transverse relation to said filaments to the circumference of said drum in overlying relationship to said first condensed mat; spinning an overlying second condensed filamentous mat by reciprocating said filament feeder axially back and forth along said drum while rotating said drum a multiplicity of times during each traverse of said feeder, and feeding a plurality of filaments from said feeder to said drum during each traverse to build up said second condensed filamentous mat containing a plurality of layers of filaments with the filaments of adjacent layers lying in crossing relationship; applying a binder to the filaments of said first and second condensed mat during the period said filaments are being fed to said drum; axially slitting said first and second condensed mat and unwrapping said mats together from said drum as an integral condensed mat containing said tubes therewithin; progressively stretching said integral condensed mat in a direction generally transverse to the lay of said filaments to form an elongate, expanded thickness web; simultaneously with said stretching step, feeding a reinforcing element through each of said tubes and interiorly of said expanded thickness web for passage therewith; and treating said expanded thickness web to cure said binder.

2. The method of making a filamentous web of the character described comprising: spinning a first condensed filamentous mat containing a plurality of layers of filaments with the filaments of the adjacent layers 1ying in crossing relationship by simultaneously reciprocating a filament feeder axially back and forth along a drum, rotating said drum a multiplicity of times during each traverse of said feeder, and feeding a plurality of laments from eaid feeder to said drum during each traverse to build up said first condensed mat; temporarily terminating said spinning operation; securing a series of circumferentially spaced, generally axially extending tubes to the circumference of said drum in overlying relationship to said first condensed mat; spinning an overlying second condensed filamentous mat containing a plurality of layers of filaments with the filaments of adjacent layers lying in crossing relationship by simultaneously reciprocating said filament feeder axially back and forth along said drum, rotating said drum a multiplicity of times during each traverse of said feeder, and feeding a plurality of filaments from said feeder to said drum during each traverse to build up said second condensed mat; applying a binder to the filaments of said first and second condensed mats; slitting said first and second condensed mat in an axial direction and unwrapping said mats together from said drum with the tubes held therewithin to form an integral planar condensed mat; elongating said integral condensed planar mat in a direction generally transverse to the lay of said filaments to form an expanded thickness web of substantially reduced width; advancing a series of adhesively coated reinforcing filaments through said tubes and into said expanded thickness web at laterally spaced intervals across the width of said web; and

6 treating said expanded thicknessweb to cure said binder and said adhesively coated reinforcing filaments.

3. The method of making a filamentous web as specified in claim'Z including: securing said tubes in a space limited circumferentially to less than half thecircumferential surface area of said drum; and slitting said mat axially on aline diametrically opposite to the axial center portion of thearea spanned by said tubes.

4. The method'of making a filamentous web 'of'the character described comprising: spinning a first cylindrical condensed 'filamentous'mat comprised of a series of overlying layers having filaments in each layer lying in crossing relationship to filaments of adjacent layers by feeding such filaments from "an axially reciprocating feederto a drum rotating amultiplicity of times during each feeder traverse; applying a series of tubes to the outer surface of said first mat and positioning said tubes in circumferentially spaced and generally axially extending relationship to said drum, with the opposite ends of said tubes extending beyond the correspondingly opposite circumferential edges of said first mat; spinning a second cylindrical condensed filamentous mat over said first cylindrical condensed filamentous mat, said second mat being comprised of another series of overlying layers having filaments in each layer lying in crossing relationship to the filaments of adjacent layers by feeding filaments from said axially reciprocating feeder to said drum rotating a multiplicity of times during each feeder traverse, the inner layer of said second mat comprising filaments lying in generally crossing relationship to the filaments comprising the outer layer of said first mat; applying a binder to the first and second condensed mats during spinning thereof; axially slitting said first and second condensed mats and unwrapping said mats together from said drum to form an integral condensed planar mat containing said tubes therewithin; progressively stretching said integral condensed mat in a direction generally transverse to the lay of said filaments and generally parallel to the lay of said tubes to form an elongate, expanded thickness web; passing a series of reinforcing filaments through said tubes into said expanded thickness web in the direction of web advance and at a rate corresponding to the rate of said web advance concurrently with said stretching step; applying an adhesive coating to said reinforcing filaments prior to passing them into said web; compressing said expanded thickness Web containing said reinforcing filaments to a predetermined desired thickness; and applying heat to said expanded thickness web to cure the binder and adhesive coating on said reinforcing filaments.

5. The method of making a filamentous web of the character described comprising: successively forming a plurality of separate, concentrically arranged, cylindrical condensed filamentous mats on a rotatable drum, each condensed mat comprising a plurality of layers of filaments with the filaments of adjacent layers lying in generally crossing relationship; interposing a series of spaced hollow members in crossing disposition to said filaments between adjacent ones of said successively formed condensed mats; slitting said plurality of condensed mats in an axial direction relative to said drum and unwrapping them together from said drum to form a planar composite condensed mat of said cylindrical condensed mats with said hollow members contained therewithin; stretching said planar mat in a direction generally transverse to the lay of said filaments; and, simultaneously with said stretching step, feeding continuous elements through said hollow members and into the filamentous Web formed by said stretching step for passage therewith.

6. The method of making a filamentous web as specified in claim 5 including: securing said hollow members in a space limited circumferentially to less than half the circumferential surface area of said drum; and slitting said mat axially on a line diametrically opposite to the axial center portion of the area spanned by said hollow members.

7. The method of making a filamentous web comprising: forming a succession of separate, concentric, cylindrical condensed filamentous mats on a rotating drum, each mat comprising a series of overlying layers having filaments in each layer lying in crossing relationship to filaments of adjacent layers; positioning at least one tube in crossing disposition to said filaments on the outer surface of each cylindrical condensed mat before the next successive overlying cylindrical mat is formed, said tube extending for substantially the axial length of said cylindrical condensed mat; axially slitting said cylindrical condensed mats and unwrapping them together from said drum to form a planar composite condensed m'at'containing said tube; progressively stretching said planar composite mat in a direction generally transverse to the lay of said filaments to form an elongated web; passing a continuous filament through said tube and into said elongating web concurrently with said stretching step.

8. The method of making a filamentous web as specified in claim 7 including: positioning a plurality of tubes between said successive cylindrical condensed mats with the ends of said tubes at one end of said drum being more closely spaced circumferentially than at the other end of said drum.

References Cited in the file of this patent UNITED STATES PATENTS 

5. THE METHOD OF MAKING A FILAMENTOUS WEB OF THE CHARACTER DESCRIBED COMPRISING: SUCCESSIVELY FROMING A PLURALITY OF SEPARATE, CONCENTRICALLY ARRANGED, CYLINDRICAL CONDENSED FILAMENTOUS MATS ON A ROTATABLE DRUM, EACH CONDENSED MAT COMPRISING A PLURALITY OF LAYERS OF FILAMENTS WITH THE FILAMENTS OF ADJACENT LAYERS LYING IN GENERALLY CROSSING RELATIONSHIP; INTERPOSING A SERIES OF SPACED HOLLOW MEMBERS IN CROSSING DISPOSITION TO SAID FILAMENTS BETWEEN ADJACENT ONES OF SAID PLURALITY OF CONDENSED MATS IN DENSED MATS; SLITTING SAID PLURALITY OF CONDENSED MATS IN AN AXIAL DIRECTION RELATIVE TO SAID DRUM AND UNWRAPPING THEM TOGETHER FROM SAID DRUM TO FORM A PLANAR COMPOSITE CONDENSED MAT OF SAID CYLINDRICAL CONDENSED MATS WITH SAID HOLLOW MEMBERS CONTAINED THEREWITHIN; STRECHING SAID PLANAR MAT IN A DIRECTION GENERALLY TRANSVERSE TO THE LAY OF SAID FILAMENTS; AND, SIMULTANEOUSLY WITH SAID STRETCHING STEP, FEEDING CONTINUOUS ELEMENTS THROUGH SAID HOLLOW MEMBERS AND INTO THE FILAMENTOUS WEB FORMED BY SAID STRETCHING STEP FOR THEREWITH. 